Designing Cost-Effective Highly Available Azure SQL Database
Short answer
A Use Azure SQL Database Business Critical to ensure synchronous replication for zero data loss and zone redundancy for high availability at a lower cost than Hyperscale.
Question
• Failover between replicas of the database must occur without any data loss.
• The database must remain available in the event of a zone outage.
• Costs must be minimized.
Which deployment option should you use?
Key Takeaways
The trap is choosing Hyperscale for its advanced features; however, Business Critical is the minimum cost tier that still provides synchronous replication and zone redundancy.
Learn why Azure SQL Database Business Critical is the optimal choice for highly available, zone-redundant deployments with zero data loss while minimizing costs compared to Hyperscale or Managed Instance.
Common mistake: Choosing Option D (Hyperscale) because it sounds like the 'highest' performance tier, ignoring the explicit instruction to minimize costs where Business Critical suffices.
Expert Analysis
Requirement Analysis The question requires a deployment option for Azure SQL Database that satisfies three constraints: zero data loss during failover, zone outage availability, and minimized costs.
Evaluating the Options
- Option A (Azure SQL Database Business Critical) is the correct choice. This tier uses synchronous replication across multiple replicas within the same region, ensuring an RPO of zero (no data loss) during automatic failovers. It supports zone-redundant configurations to survive datacenter outages. While more expensive than General Purpose, it is significantly cheaper than Hyperscale or Managed Instance equivalents, satisfying the cost minimization requirement relative to higher-tier options.
- Option C (Azure SQL Database Standard) is incorrect because it does not offer zone redundancy or synchronous replica failover with zero data loss. It is designed for lower availability needs.
- Option D (Azure SQL Database Hyperscale) offers high scalability and zone redundancy but is architected for massive scale-out workloads. Its storage and compute costs are generally higher than Business Critical for standard-sized databases, violating the "minimize costs" constraint when High Availability is the primary goal.
- Option B (Azure SQL Managed Instance Business Critical) provides similar HA features but is a PaaS offering with a larger footprint and typically higher cost than a single Azure SQL Database instance, making it less optimal for cost minimization unless specific VNet isolation or legacy compatibility is required.
Conclusion Business Critical is the most cost-effective tier that natively delivers synchronous replication and zone redundancy.
Exam Strategy
When designing for High Availability in Azure, always check the replication type first. Synchronous replication (Business Critical) is required for zero RPO. If the question asks to 'minimize costs' alongside HA, compare Business Critical against Hyperscale and Managed Instance, selecting the lowest-cost tier that meets the technical HA requirements.
Frequently Asked Questions
Does Azure SQL Database Business Critical support zone redundancy?
Why not use Standard tier for high availability?
Community Votes
100% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 1 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 1
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AllanHouston 👍 1 Answered AThe correct answer is indeed Azure SQL Database Business Critical No data loss during failover: Business Critical uses multiple synchronously replicated replicas. A transaction is committed only after replication, providing an RPO of zero for replica failover. Zone-outage protection: Enabling zone redundancy places replicas across separate availability zones within the Azure region. Lower cost than Managed Instance Business Critical: A single Azure SQL Database avoids the additional instance-level capacity and capabilities of Azure SQL Managed Instance that this scenario does not require. Standard is unsuitable: The Standard DTU tier does not support zone redundancy. Hyperscale is unnecessary: Hyperscale can be zone redundant, but its scale-out storage architecture and separately billed high-availability replicas are unnecessary for the stated requirements.
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